Method of operating an internal combustion engine

ABSTRACT

An internal combustion engine in for a motor vehicle in ( 1 ) is described. The internal combustion engine ( 1 ) has an injection valve with which fuel can be injected directly into a combustion chamber either during a compression phase in a first operating mode or during an intake phase in a second operating mode. In addition, a control unit is provided for shifting between the two operating modes and for differential control and/or regulation of the performance quantities that influence the actual moment of the internal combustion engine in both operating modes as a function of a setpoint moment. A change in the actual moment during a shifting operation is determined by the control unit and at least one of the performance quantities is influenced by the control unit as a function thereof.

FIELD OF THE INVENTION Background Information

The present invention relates to a method of operating an internalcombustion engine in a motor vehicle in particular, where fuel isinjected directly into a combustion chamber either during a compressionphase in a first operating mode or during an intake phase in a secondoperating mode, where shifting takes place between the two operatingmodes, and where the performance quantities that influence the actualmoment of the internal combustion engine are controlled and/or regulateddifferently as a function of a setpoint moment in both operating modes.In addition, the present invention concerns an internal combustionengine for a motor vehicle in particular, having an injection valve withwhich fuel can be injected directly into a combustion chamber eitherduring a compression phase in a first operating mode or during an intakephase in a second operating mode, and having a control unit for shiftingbetween the two operating modes and for differential control and/orregulation of performance quantities that influence the actual moment ofthe internal combustion engine in both operating modes as a function ofa setpoint moment.

Systems for direct injection of fuel into the combustion chamber of aninternal combustion engine are conventional in general. A distinction ismade between stratified operation as a first operating mode andhomogeneous operation as the second mode. Stratified operation is usedat relatively low loads on the internal combustion engine in particular,while homogeneous operation is used at relatively high loads.

In stratified operation, fuel is injected into the combustion chamberduring the compression phase of the internal combustion engine, so thereis a cloud of fuel in the immediate vicinity of a sparkplug at the timeof ignition. This injection may occur in various ways. For example, itis possible for the injected cloud of fuel to be at the sparkplug and beignited by it during or immediately after injection. It is also possiblefor the injected cloud of fuel to be carried to the sparkplug by themotion of a charge and only then ignited. There is not a uniformdistribution of fuel with either combustion method, but instead there isa stratified charge.

The advantage of stratified operation is that the internal combustionengine can handle lower loads with a very small amount of fuel. However,higher loads cannot be handled by stratified operation.

In homogeneous operation which is intended for such higher loads, fuelis injected during the intake phase of the internal combustion engine,so that turbulence can be created in the fuel, which is thus readilydistributed in the combustion chamber. Homogeneous operation thuscorresponds approximately to the operation of internal combustionengines where fuel is injected into the intake manifold in thetraditional manner. If necessary, homogeneous operation may also be usedat lower loads.

In stratified operation, the throttle valve in the intake manifoldleading to the combustion chamber is opened wide, and combustion iscontrolled and/or regulated only by the fuel mass to be injected. Inhomogeneous operation, the throttle valve is opened and closed as afunction of the required moment, and the fuel mass to be injected iscontrolled and/or regulated as a function of the air flow intake.

In both operating modes, i.e., in stratified operation and inhomogeneous operation, the fuel mass to be injected is additionallycontrolled and/or regulated at an optimum level from the standpoint ofsaving fuel, reducing exhaust, etc., as a function of a plurality ofadditional performance quantities. The control and/or regulation here isdifferent in both operating modes.

The internal combustion engine must be shifted from stratified operationto homogeneous operation and back again. In stratified operation, thethrottle valve is opened wide, and air is thus supplied largely withoutthrottling, but in homogeneous operation the throttle valve is onlypartially opened, thus reducing the supply of air. Especially whenshifting from stratified operation to homogeneous operation, the abilityof the intake manifold leading to the combustion chamber to store airmust be taken into account. If this is not taken into account, shifting(from one type of operation to another) can lead to an increase in themoment delivered by the internal combustion engine.

SUMMARY

The object of this present invention is to provide a method foroperating an internal combustion engine so that improved shiftingbetween the operating modes is possible.

This object is achieved with a method of the type defined in and with aninternal combustion engine according to the present invention bydetermining a change in the actual moment during a shifting operationand influencing at least one of the performance quantities as a functionthereof.

On the basis of the determination of changes in the actual moment duringthe shifting operation, it is possible to detect irregular running orbucking while shifting. After bucking has been detected, the irregularrunning can be counteracted by influencing performance quantities. It isthus possible to prevent irregular running or bucking when shifting fromhomogeneous operation to stratified operation or vice versa. Shiftingoperations between the two operating modes are thus improved inparticular with regard to smoother running and thus greater comfort.

In an advantageous embodiment of the present invention, the change inthe actual moment is determined when shifting from the first operatingmode to the second. This is a simple but effective method of detectingchanges in the actual moment in a quasi-steady-state manner.

In another advantageous embodiment of the present invention, the changein the actual moment is determined in particular in succession atdifferent fillings of the combustion chamber. In this way, dynamicshifting jerk is detected in a quasi-steady-state manner in dynamicoperation of the internal combustion engine. This shifting jerk can becounteracted in the sense of minimizing it by dynamically influencingthe performance quantities of the internal combustion engine.

In an advantageous embodiment of the present invention, the change inthe actual moment is determined as a function of the measured rpm of theinternal combustion engine. This achieves the result that a change inthe actual moment and thus any bucking, etc., can be detected with thehelp of the rpm sensor which is already present anyway. This avoids theneed for additional sensors or other additional components.

In an advantageous embodiment of the present invention, irregularrunning values are determined for the individual cylinders. Changes inthe actual moment of the internal combustion engine can be deduced fromthese irregular running values. It is thus possible with the help ofirregular running values to detect fluctuations in rpm or bucking of aninternal combustion engine. Irregular running values can be determinedin various ways. It is thus possible to provide an irregular runningsensor to measure the irregular running values. Likewise, irregularrunning values can be derived from the rpm of the internal combustionengine, for example. It is important that irregular running valuesrepresent a measure of differences in torque between successivecylinders.

In an advantageous embodiment of the present invention, first only oneof the cylinders is shifted, and thereafter at least one of theirregular running values of the shifted cylinder is compared with atleast one of the irregular running values of at least one of the othercylinders. It is thus possible to determine whether there is adifference in torque between the shifted cylinder and cylinders thathave not yet been shifted. In this way it is possible to determinewhether there can be a difference in torque between the two operatingmodes between which the cylinders are to be shifted and thus whetherbucking may occur.

It is especially advantageous if the other cylinders are to be shiftedor not shifted as a function of the comparison. If the irregular runningvalues of the shifted cylinder deviate significantly from the irregularrunning values of the cylinder not shifted, shifting can be suppressedto reliably prevent bucking of the internal combustion engine in thisway. However, if there is no significant deviation, the other cylinderscan also be shifted to the other operating mode. In this case, nobucking of the internal combustion engine is to be expected on the basisof the minor difference in irregular running values.

In an advantageous embodiment of the present invention, performancequantities of the internal combustion engine are influenced as afunction of this comparison. Thus, when a deviation in irregular runningvalues of a shifted cylinder from the irregular running values of theother cylinders is found, it is possible for the performance quantitiesof the internal combustion engine to be influenced in such a way as tominimize or eliminate this deviation. Shifting that has been started canbe terminated to prevent bucking of the internal combustion engine.However, it is also possible to complete shifting, so that performancequantities are not influenced until subsequent shifting.

In an advantageous embodiment the influence on one of the performancequantities is implemented adaptively. There is thus a permanentcorrection of the shifting operation. It is thus possible, for example,to compensate for changes in the internal combustion engine, inparticular wear phenomena, etc., over its lifetime. It is also possibleto compensate for deviations between different internal combustionengines of the same type during startup.

In another advantageous embodiment of the present invention, theinfluence on one of the performance quantities is not implemented untilthe next shifting operation. This achieves the result that calculationsaccording to the present invention can be performed between two shiftingoperations, so that sufficient time is available for them.

It is especially advantageous if the injected fuel mass is influenced inthe sense of an increase in particular in the first operating mode. Itis also advantageous if in the second operating mode, the firing angleand/or the firing point is influenced in the sense of a retardadjustment in particular. Due to these measures it is possible toinfluence the actual moment of the internal combustion engine whenirregular running is detected during the shifting operation and thusreduce the irregular running. In particular, the two operating modesapproach one another at the shifting point as a result of thesemeasures.

Implementation of the method according to the present invention in theform of a control element provided for a control unit of an internalcombustion engine in a motor vehicle in particular may be especiallyimportant. A program stored on the control element can be run on aprocessor, in particular a microprocessor, and is suitable for carryingout the method according to the present invention. In this case theinvention is thus implemented by a program stored on the controlelement, so this control element with the program represents the presentinvention in the same way as the method which the program is suitablefor executing. In particular, an (electronic) storage medium such as aread-only memory can be used as the control element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic block diagram of one embodiment of an internalcombustion engine according to the present invention in a motor vehicle.

FIG. 2 shows a schematic flow chart of one embodiment of a methodaccording to the present invention for operating the internal combustionengine according to FIG. 1,

FIG. 3 shows a schematic time chart of signals of the internalcombustion engine of FIG. 1 when carrying out the method according toFIG. 2,.

FIG. 4 shows a schematic time chart of signals of the internalcombustion engine of FIG. 1 when carrying out a method opposite to thatof FIG. 2, and

FIG. 5 shows a schematic flow chart of an embodiment of a methodaccording to the present invention for shifting according to FIGS. 2 and3.

DETAILED DESCRIPTION

FIG. 1 shows an internal combustion engine 1 having a piston 2 movingback and forth in a cylinder 3. Cylinder 3 has a combustion chamber 4connected by valves 5 to an intake manifold 6 and an exhaust pipe 7. Inaddition, combustion chamber 4 has an injection valve 8 controlled by asignal TI and a sparkplug 9 controlled by a signal ZW.

Intake manifold 6 has an air flow sensor 10, and exhaust pipe 7 may havea lambda sensor 11. Air flow sensor 10 measures the air flow of freshair supplied to intake manifold 6 and generates a signal LM as afunction thereof. Lambda sensor 11 measures the oxygen content of theexhaust gas in exhaust pipe 7 and generates a signal λ as a functionthereof.

A throttle valve 12 is accommodated in intake manifold 6 and itsrotational position can be adjusted by a signal DK.

Throttle valve 12 is opened wide in a first operating mode, stratifiedoperation of internal combustion engine 1. Fuel is injected by injectionvalve 8 into combustion chamber 4 during a compression phase created bypiston 2, specifically being injected locally into the immediatevicinity of sparkplug 9 and at a suitable interval before the ignitionpoint. Then, the fuel is ignited by sparkplug 9 to drive piston 2 by theexpansion of the ignited fuel in the subsequent working phase.

In a second operating mode, homogeneous operation of internal combustionengine 1, throttle valve 12 is opened or closed partially as a functionof the desired air flow supplied. Fuel is injected by injection valve 8into combustion chamber 4 during an intake phase created by piston 2.Due to concomitant air intake, turbulence is created in the injectedfuel, thus distributing it essentially uniformly throughout combustionchamber 4. Next the fuel/air mixture is compressed during thecompression phase and then ignited by sparkplug 9. Piston 2 is driven bythe expansion of the ignited fuel.

In stratified operation as well as in homogeneous operation, arotational motion is induced in a crankshaft 14 by the driven piston,ultimately driving the wheels of the motor vehicle. An rpm sensor 15 isprovided for crankshaft 14, generating a signal N as a function ofrotational motion of crankshaft 14.

Fuel mass injected into combustion chamber 4 by injection valve 8 instratified operation and in homogeneous operation is controlled and/orregulated by a control unit 16 with regard to low fuel consumptionand/or low pollution emission in particular. To this end, control unit16 is fitted with a microprocessor having a program suitable forexecuting aforesaid control and/or regulation stored in a memory medium,specifically a read-only memory.

Control unit 16 receives input signals representing performancequantities of the internal combustion engine measured by sensors. Forexample, control unit 16 is connected to air flow sensor 10, lambdasensor 11 and rpm sensor 15. In addition, control unit 16 is connectedto a gas pedal sensor 17 generating a signal FP to indicate the positionof a driver-operated gas pedal and thus the moment requested by thedriver. Control unit 16 generates output signals with which theperformance of the internal combustion engine can be influenced byactuators according to the desired control and/or regulation. Forexample, control unit 16 is connected to injection valve 8, sparkplug 9and throttle valve 12, generating signals TI, ZW and DK required forcontrolling them.

The method of shifting from stratified operation to homogeneousoperation described below with reference to FIGS. 2 and 3 is carried outby control unit 16. Blocks shown in FIG. 2 represent functions of themethod implemented, e.g., in the form of software modules or the like,in control unit 16.

In FIG. 2, it is assumed in a block 21 that internal combustion engine 1is in a steady-state stratified operation. Then in a block 22, atransition to homogeneous operation is requested, e.g., on the basis ofacceleration in the vehicle desired by the driver. FIG. 3 also shows thetime of the request for homogeneous operation.

Then, debouncing is performed by blocks 23, 24, preventing rapidshifting back and forth between stratified operation and homogeneousoperation. When homogeneous operation is enabled, the transition fromstratified operation to homogeneous operation is started by a block 25.The time when the shifting operation begins is labeled with referencenumber 40 in FIG. 3.

At time 40, throttle valve 12 is controlled by a block 26 out of itscompletely opened state wdksch in stratified operation into an at leastpartially opened or closed state wdkhom for homogeneous operation. Therotational position of throttle valve 12 in homogeneous operation isoriented at a stoichiometric fuel/air mixture, i.e., at λ=1, and alsodepends on, e.g. the requested moment and/or rpm N of internalcombustion engine 1, etc.

Through the adjustment of throttle valve 12, internal combustion engine1 goes from steady-state stratified operation into a non-steady-statestratified operation. In this operating state, the air flow supplied tocombustion chamber 4 drops gradually from a filling rlsch duringstratified operation to smaller fillings. This is shown in FIG. 3. Airflow rl supplied to combustion chamber 4 or the filling of thecombustion chamber is determined by control unit 16, inter alia, fromsignal LM of air flow sensor 10. According to a block 27, internalcombustion engine 1 is still operated in stratified operation.

Then, a block 28 in FIG. 2 triggers a shift to a non-steady-statehomogeneous operation. This is the case at time 41 in FIG. 3.

According to a block 29, fuel mass rk injected into combustion chamber 4in homogeneous operation is controlled and/or regulated as a function ofair flow rl supplied to combustion chamber 4 so that in particular astoichiometric fuel/air mixture is obtained, i.e., λ=1. However, it isalso possible for the fuel/air mixture to be adjusted to be rich orlean, i.e., to select λ>1 or λ<1.

Fuel mass rk influenced in this way results in moment Md delivered byinternal combustion engine 1 being increased—at least for a certainperiod of time. This is compensated by the fact that at time 41, i.e.,when shifting to homogeneous operation, firing angle ZW is adjusted fromvalue zwsch so that delivered moment Md maintains a setpoint momentmdsoll derived from the requested moment, among other things, and thusit remains approximately constant.

To this end, fuel mass rk is determined from air flow rl supplied tocombustion chamber 4 under the assumption of a stoichiometric fuel/airmixture. In addition, firing angle ZW is adjusted in the direction ofretarded firing as a function of setpoint moment mdsoll. With regard tothis retard adjustment, there is thus a certain deviation from normalhomogeneous operation with which the excessive air flow supplied and theresulting excess moment generated of internal combustion engine 1 aretemporarily dissipated.

A check is performed in a block 30 to determine whether air flow rlsupplied to combustion chamber 4 has finally dropped to the fillingbelonging to steady-state homogeneous operation at a stoichiometricfuel/air mixture. If this is not yet the case, waiting is continued in aloop over block 29. However, if this is the case, operation of internalcombustion engine 1 is continued in steady-state homogeneous operationwithout a firing angle adjustment by block 31. This is the case in FIG.3 at a time labeled with reference number 42.

In this steady-state homogeneous operation, the air flow supplied tocombustion chamber 4 corresponds to filling rlhom for homogeneousoperation, and firing angle zwhom for sparkplug 9 also corresponds tothat for homogeneous operation. The same also applies to rotationalposition wdkhom of throttle valve 12.

FIG. 3 shows steady-state stratified operation as range A,non-steady-state stratified operation as range B, non-steady-statehomogeneous operation as range C and steady-state homogeneous operationas range D. FIG. 4 shows shifting from homogeneous operation tostratified operation, where there is to be a shift to steady-statestratified operation from steady-state homogeneous operation on thebasis of the performance quantities, for example, of internal combustionengine 1.

Shifting to stratified operation is initiated by control unit 16 bywithdrawing the request for homogeneous operation. After debouncing,shifting to stratified operation is enabled, and throttle valve 12 iscontrolled to move into the rotational position intended for stratifiedoperation. This is a rotational position at which throttle valve 12 ismostly open. This is represented by the transition from wdkhom to wdkschin FIG. 4.

It is possible for this transition to be processed further by controlunit 16 with or without taking into account a throttle valve overshoot.This is represented by solid or dotted lines in FIG. 4.

Opening throttle valve 12 results in increased air flow rl supplied tocombustion chamber 4. This is apparent from the curve for rlhom in FIG.4. The shift from the non-steady-state homogeneous operation describedhere to non-steady-state stratified operation takes place after this.This is the case at time 43 in FIG. 4.

Before shifting to stratified operation, the increasing air flowsupplied to combustion chamber 4 is compensated by increasing injectedfuel mass rk and adjusting firing angle ZW to be retarded. This isapparent from the curves for rkhom and zwhom in FIG. 4.

After shifting to stratified operation, injected fuel mass rk is set atvalue rksch for stratified operation. The same applies to firing angleZW which is set at value zwsch for stratified operation.

FIG. 4 shows steady-state homogeneous operation as range A,non-steady-state homogeneous operation as range B, non-steady-statestratified operation as range C and steady-state stratified operation asrange D.

FIG. 5 illustrates a method that can be employed when shifting fromstratified operation to homogeneous operation according to FIGS. 2 and3. This method is used to detect changes in torque of internalcombustion engine 1, i.e., changes in actual moment Md delivered duringthe shifting operation. The blocks shown in FIG. 5 represent functionsof the method implemented, e.g., in the form of software modules or thelike in control unit 16.

According to a block 51, it is assumed that internal combustion engine 1is in steady-state stratified operation. Shifting from stratifiedoperation to homogeneous operation is started in a block 52.

The method described below for detecting and minimizing jerking thatoccurs dynamically when shifting is carried out as a quasi-steady-statemethod at different fillings rlgrenz in succession.

To this end, a limit value rlgrenz for the filling of combustion chamber4 is selected in a block 53 so that this limit value rlgrenz can be usedin both stratified and homogeneous operation.

According to a block 54, throttle valve 12 is closed. This results in areduced air flow rl supplied to the combustion chamber and thus reducedfilling in the combustion chamber. Pressure ps in intake manifold 6 ofinternal combustion engine 1, from which filling rl can be derived, isreduced because throttle valve 12 is closed. Regardless of thesechanges, internal combustion engine 1 is operated further in stratifiedoperation according to block 55.

A check is performed in a block 56 to determine whether filling rl incombustion chamber 4 has dropped to limit value rlgrenz, i.e., whetherrl≦rlgrenz. If this is not yet the case, the method is continued withblock 54, i.e., in particular with further operation of internalcombustion engine 1 in stratified operation according to block 55.

If rl≦rlgrenz, i.e., if filling rl in combustion chamber 4 of internalcombustion engine 1 has reached limit value rlgrenz, then pressure ps inintake manifold 6 is kept approximately constant according to a block57. This can be accomplished, e.g., by a suitable influence on throttlevalve 12.

Then, in a block 58, one of cylinders 3 of internal combustion engine 1,e.g., the x-th cylinder, is shifted to homogeneous operation. However,all other cylinders 3 of internal combustion engine 1 remain instratified operation.

According to a block 59, fuel mass rk is supplied to x-th cylinder 3 asa function of filling rl in combustion chamber 4 and for astoichiometric fuel/air mixture, i.e., for λ=1. In addition, firingangle ZW or the firing point of x-th cylinder 3 is adjusted to beretarded as a function of setpoint moment mdsoll. Torque Md that wouldresult due to injected fuel mass rk is thus reduced to the desired levelof setpoint moment mdsoll by this retard adjustment.

Then, irregular running values are determined in a block 60. Theseirregular running values may be any values characterizing smooth orirregular running of internal combustion engine 1. For example, it ispossible to provide internal combustion engine 1 with a sensor to detectsmooth or irregular running of internal combustion engine 1. It islikewise possible for the irregular running of internal combustionengine 1 to be determined from other performance quantities of internalcombustion engine 1, in particular those that are already available. Inparticular, it is possible for the irregular running to be calculatedfrom rpm N of internal combustion engine 1.

The smooth or irregular running of internal combustion engine 1represents a measure of changes in actual moment Md of internalcombustion engine 1. In particular, the smooth or irregular runningrepresents a measure of the differences in torque between successivelyfired cylinders 3 of internal combustion engine 1. To this end, it ispossible to assign the smooth or irregular running to individualcylinders 3 of internal combustion engine 1.

A method of determining the smooth or irregular running of internalcombustion engine 1 is explained below. It should be pointed outexplicitly that the method described here is given only as an exampleand can be replaced and/or supplemented by any other methods ofdetermining smooth or irregular running.

To determine irregular running of internal combustion engine 1, segmenttimes ts are measured during the operation of internal combustion engine1. One segment time ts is measured with each combustion. A number n isassigned to each combustion, and the respective segment time ischaracterized as ts(n) accordingly. For example, a crankshaft angle of360 degrees divided by half the number of cylinders is selected as asegment and assigned to each cylinder 3 of internal combustion engine 1.In particular, it is possible to arrange the segment symmetrically withthe top dead center of respective cylinder 3.

Segment times ts(n) which depend on combustion are detected, e.g., withthe help of a sensor which measures the duration of the passing of therespective segment past a reference point. The sensor may be rpm sensor15 in particular. Segment times ts(n) measured by the sensor at the sametime represent rpm information from which the rpm characteristic andthus also rpm fluctuations can be derived for respective cylinder 3.

By using comparison functions and optionally adaption functions, it ispossible to determine system-induced fluctuations in rpm and have themcompensated or disregarded in the calculation of irregular running[values]. These may be, for example, manufacturing tolerances orvibrations or the like. Such compensated segment times tsk(n) thusdepend essentially only on fluctuations in torque for the individualcylinder.

The irregular running value is calculated from these compensated segmenttimes tsk(n), for example, as follows:

lut(n)=(tsk(n+1)−tsk(n)/tsk(n)³)

For each power stroke, j irregular running values lut(z, j) for eachindividual cylinder are obtained by assigning irregular running valueslut(n), numbered continuously according to combustions n, to a number zof cylinders 3 of internal combustion engine 1, for example. Theseirregular running values lut(z, j) can be filtered by using appropriatealgorithms. For example, it is possible to perform a low-pass filteringto suppress stochastic interference. Such filtered irregular runningvalues flut(z, j) for each individual cylinder represent theabove-mentioned measure of differences in torque between successivelyfired cylinders 3 of internal combustion engine 1.

If irregular running values lut(n) and/or lut(z, j) and/or flut(z, j)have been determined in block 60, for example, by the method describedhere, these values are used further in the method described below. Asmentioned previously, however, irregular running values determined byother methods may also be used accordingly in the method describedbelow.

A check is performed in a block 61 to determine whether the irregularrunning value of cylinder x, which has already been shifted tohomogeneous operation, differs greatly or significantly from theirregular running values of the other cylinders. A threshold value canbe selected for the difference in irregular running values; whenexceeded, there is a significant deviation.

If cylinder x, which has already been shifted to homogeneous operation,does not have any significant deviation with regard to its irregularrunning values in comparison with the other cylinders, then the othercylinders are also shifted to homogeneous operation in a block 62. In adownstream block 63, throttle valve 12 is set at a steady-state valuefor homogeneous operation, and internal combustion engine 1 is operatedfurther in steady-state homogeneous operation. In addition, detection ofjerking in a block 64 is terminated.

However, if the irregular running values of cylinder x, which hasalready been shifted to homogeneous operation, differ significantly fromthe irregular running values of the other cylinders, a difference inmoment for each cylinder, characterizing the difference betweenstratified operation and homogeneous operation for this cylinder, isdetermined in a block 65 from the difference in irregular runningvalues.

On the basis of this cylinder-specific difference in moment, the momentcontrol is influenced adaptively in a block 66. For example, thedifference in moment between stratified operation and homogeneousoperation can be minimized or reduced to zero by a change in the retardadjustment of firing angle ZW. The same can also be achieved byinfluencing fuel mass rk supplied.

After block 66, internal combustion engine 1 can be returned tosteady-state stratified operation again. Thus, in this case it is notshifted completely to homogeneous operation, but instead cylinder x,which is the only cylinder already shifted to homogeneous operation, isshifted back to stratified operation. This procedure is then continuedvia arrow 67 with block 51, with a new limit value rlgrenz beingselected in block 53 for the filling of combustion chamber 4.

As an alternative, internal combustion engine 1 may also be shiftedcompletely to homogeneous operation after block 66. Then the othercylinders are also shifted to homogeneous operation. This is indicatedwith arrow 68 in FIG. 5.

If changes in actual moment Md of internal combustion engine 1 duringthe shifting operation are detected by the method according to FIG. 5,countermeasures are taken in block 66, as mentioned previously. Thesecountermeasures generally involve changes in performance quantities ofinternal combustion engine 1 with which actual moment Md of internalcombustion engine 1 is influenced.

In shifting from stratified operation to homogeneous operation accordingto FIGS. 2 and 3, firing angle ZW or the firing point is adjusted to beretarded when changes in torque are found in range C so as to compensatefor excessive filling rl of combustion chamber 4 as well as thedifference in moment detected at this point and thus to reduce changesin torque. The same applies to shifting from homogeneous operation tostratified operation in range B in FIG. 4. Such changes in torque aredynamic torque changes that can be corrected permanently by adaptivechanges in the above-mentioned performance quantities.

When changes in torque are found in range C when shifting fromhomogeneous operation to stratified operation according to FIG. 4, fuelmass rk to be injected into combustion chamber 4 is reduced or increasedin such a way as to reduce the determined torque changes. The same istrue of shifting from stratified operation to homogeneous operation inrange B in FIG. 3. Such changes in torque are dynamic torque changeswhich can be corrected permanently by adaptive changes in theabove-mentioned performance quantities.

The above-mentioned influences on performance quantities of internalcombustion engine 1 to compensate for irregular running or buckingduring a shifting operation can be performed immediately, so there maybe an effect during the instantaneous shifting operation. However, it isalso possible for the influences to be implemented in such a way thatthe effect does not occur until the next shifting operation.

What is claimed is:
 1. A method of operating an internal combustionengine in a motor vehicle, comprising: injecting fuel directly into acombustion chamber during a compression phase in a first operating modeand during an intake phase in a second operating mode; shifting betweenthe first operating mode and the second operating mode; influencing anactual moment of the internal combustion engine as a function of atleast one of an injected fuel mass, a firing angle and a firing point;at least one of controlling and regulating at least one of the injectedfuel mass, the firing angle and the firing point differently as afunction of a setpoint moment in both of the first operating mode andthe second operating mode; determining a change in the actual momentduring the shifting between the first operating mode and the secondoperating mode; and influencing at least one of the injected fuel mass,the firing angle and the firing point as a function of the determinedchange.
 2. The method according to claim 1, wherein the determining stepincludes determining the change in the actual moment when shifting fromthe first operating mode to the second operating mode.
 3. The methodaccording to claim 1, wherein the determining step includes determiningthe change in the actual moment in succession at different fillings ofthe combustion chamber.
 4. The method according to claim 1, wherein thedetermining step includes determining the change in the actual moment asa function of a measured rpm of the internal combustion engine.
 5. Themethod according to claim 1, wherein the second influencing stepincludes adaptively influencing at least one of the injected fuel mass,the firing angle and the firing point.
 6. The method according to claim1, wherein the second influencing step includes influencing at least oneof the injected fuel mass, the firing angle and the firing point onlyafter the shifting step.
 7. The method according to claim 1, wherein thesecond influencing step includes increasing the injected fuel mass inthe first operating mode.
 8. The method according to claim 1, whereinthe second influencing step includes influencing at least one of thefiring angle and the firing point in the second operating mode with aretard adjustment.
 9. An internal combustion engine for a motor vehicle,comprising: a fuel injection valve injecting fuel directly into acombustion chamber during a compression phase in a first operating modeand during an intake phase in a second operating mode; and a controlunit shifting the internal combustion engine between the first operatingmode and the second operating mode, the control unit influencing anactual moment of the internal combustion engine as a function of atleast one of an injected fuel mass, a firing angle and a firing point,at least one of controlling and regulating at least one of the injectedfuel mass, the firing angle and the firing point differently as afunction of a setpoint moment in both of the first operating mode andthe second operating mode, the control unit determining a change in theactual moment during the shifting, and the control unit influencing atleast one of the injected fuel mass, the firing angle and the firingpoint as a function of the determined change.
 10. A method of operatingan internal combustion engine in a motor vehicle, comprising: injectingfuel directly into a combustion chamber during a compression phase in afirst operating mode and during an intake phase in a second operatingmode; shifting between the first operating mode and the second operatingmode; influencing an actual moment of the internal combustion engine asa function of at least one of an injected fuel mass, a firing angle anda firing point; at least one of controlling and regulating at least oneof the injected fuel mass, firing angle and the firing point differentlyas a function of a setpoint moment in both of the first operating modeand the second operating mode; determining a change in the actual momentduring the shifting between the first operating mode and the secondoperating mode; influencing at least one of the injected fuel mass, thefiring angle and the firing point as a function of the determinedchange; and determining irregular running values for individualcylinders of the internal combustion engine.
 11. The method according toclaim 10, wherein the shifting step includes, at first, shifting onlyone of the cylinders, the method further comprising the step ofcomparing at least one of the irregular running values of the one of thecylinders with at least one of the irregular running values of at leastone of the other cylinders.
 12. The method according to claim 11,wherein the shifting step includes shifting others of the cylinders as afunction of the comparing step.
 13. The method according to claim 12,wherein if a predetermined threshold value is exceeded, the others ofthe cylinders are not shifted.
 14. The method according to claim 11,wherein the second influencing step includes influencing at least one ofthe injected fuel mass, the firing angle and the firing point as afunction of the comparing step.